14 Three planes have equations
$$\begin{aligned}
- x + a y & = 2
2 x + 3 y + z & = - 3
x + b y + z & = c
\end{aligned}$$
where \(a\), \(b\) and \(c\) are constants.
- In the case where the planes do not intersect at a unique point,
- find \(b\) in terms of \(a\),
- find the value of \(c\) for which the planes form a sheaf.
- In the case where \(b = a\) and \(c = 1\), find the coordinates of the point of intersection of the planes in terms of \(a\).